Observing the Geminids in December
Chart showing the sky surrounding the radiant of the Geminids.
The Geminid Meteor shower is one of the most active of the year, sometimes surpassed only by the Perseids in intensity.
The shower peaks on the morning of 15 December in New Zealand. The Geminids don't seem to have a sharp peak like the
Leonids, and observations can be made for a week either side of the peak.
At it's height, the Geminids have a zenith hourly rate of about 80 meteors per hour. So, if for you the radiant was at
the zenith, and you could observe the whole sky at once, you might expect to see 80 meteors an hour.
Alas, in New Zealand, the radiant is low. In fact it lies just a degree or two to the left of, and slightly below,
Castor. So, in New Zealand we effectivly lose out on seeing 50% of the meteors before we start. But it is still a shower
worth looking at. I have found from when I lived in Auckland, and if it was fine, seeing a dozen or more Geminids an
hour around the peak was quite normal. And of course one cannot observe all the sky at once. Geminids are inclined to
leave good trains, and some of those meteors travel long distances. One I observed appeared first near Sirius, and
travelled overhead and a long way towards the southern horizon. Remember, meteors do not appear at the radiant, unless
they are heading straight for you, but generally tens of degrees from it.
The best time to look for Geminids is any time after about 1 or 2 am through until dawn. Gemini will be approaching
north. I would suggest you look for Geminids streaking through the sky in the region of Orion and the area of sky to the
right of Orion. Make sure you have a dark sky from northwest sound to east, and at least up to the zenith. Keep glow
from city lights to the south of you.
Most meteor showers are associated with cometary debris travelling in the orbit of the comets. The Geminids are a bit
different. The appear to be travelling in the same orbit as Apollo asteroid 3200 Phaethon. Is this an asteroid that
perhaps was once surrounded by and icy snowball of cometary matter?
Full post: Geminids in December